4 ms·

> that one individual who happened to be male had I don't think it works like that. I've heard it put like this: evolution is a conservative force, it keeps t

> that one individual who happened to be male had I don't think it works like that. I've heard it put like this: evolution is a conservative force, it keeps the genes that work, and remove what doesn't. I would probably think of it like this: (it's all speculation, we'll never know). Bigger mammals have bigger lungs and stomachs and deeper voice (because bigger) - thus females are the one who selects that, regardless of if they themselves are big or small (males don't care) - size trend downwards, but still selecting "upwards", so now humans are a bit smaller, male and female, size doesn't change outcome. But voice is still tied to aggression, intimidation, fighting, etc, which males are needed for to protect the females. So we keep the vocal traits while the species trends downwards in size. The "choose the voice" and "make the voice" strategy has worked for us, so keep doing that. IE: the mutation happens to both sexes, that we get smaller. It doesn't happen to one sex, "grow a deeper voice". Males would procreate with female deep voice or not. For us to develop a tail, we'd need to lose our ears (balance) and it would happen to both sexes, unfair for males to have balance and females not.

tsimionescu 5y ago
But human (and probably earlier hominid?) males have a deeper voice not because they are larger, but because the thyroid gland and larynx take on different shapes under the effect of high levels of testosterone. Therefore, deepness of voice is mostly correlated with testosterone levels (assuming no other effects, like smoke inhalation), in both males and females. It is true though that this may have started out as a coincidence, and then selective pressures could have made it more prominent. > I've heard it put like this: evolution is a conservative force, it keeps the genes that work, and remove what doesn't. My understanding is that a new gene is unlikely to become common (or even survive at all) unless it provides some measurable benefit to reproduction (which includes survival, since that is a prerequisite for reproduction, even in old age for social species), either directly or by being associated with another gene that does.

tsimionescu 5y ago

But human (and probably earlier hominid?) males have a deeper voice not because they are larger, but because the thyroid gland and larynx take on different shapes under the effect of high levels of testosterone. Therefore, deepness of voice is mostly correlated with testosterone levels (assuming no other effects, like smoke inhalation), in both males and females. It is true though that this may have started out as a coincidence, and then selective pressures could have made it more prominent. > I've heard it put like this: evolution is a conservative force, it keeps the genes that work, and remove what doesn't. My understanding is that a new gene is unlikely to become common (or even survive at all) unless it provides some measurable benefit to reproduction (which includes survival, since that is a prerequisite for reproduction, even in old age for social species), either directly or by being associated with another gene that does.